#coding=utf-8

def start(obj):
    obj.speak()

class Animal:
    def speak(self):
        print("叫啊叫，但不知何物在叫！")

class Dog(Animal):
    def speak(self):
        print("小狗🐶：汪汪叫")

class Cat(Animal):
    def speak(self):
        print("小猫🐱：喵喵叫")

class Car(Animal):
    def speak(self):
        print("小汽车🚗：滴滴叫")

start(Dog())
start(Cat())
start(Car())